A power supply is shown and described in U.S. patent application entitled "Regulated Power Supply for Very High Current" was filed on Mar. 22, 1973, Ser. No. 343,792 and continued on Mar. 14, 1974 as Ser. No. 451,302 and is further described in an application filed on July 16, 1973 and bearing Ser. No. 379,418. The present invention is particularly adapted although not limited to use with power supplies as described in the above designated applications.
In the past regulated power supplies have been available for providing regulated output voltage and current. When such power supplies are used to power sensitive equipment which would be damaged by overvoltage, it must be determined whether or not the power supply can completely control its output voltage under all load conditions. Abrupt load changes may cause harmful voltage spikes. One method which has been used to control or eliminate such spikes is the so called "crow-bar" circuit. This circuit employing an SCR, or other device capable of carrying a large current for a short time, is shunted across the output terminals of the power supply. When a spike occurs, the crow-bar shorts the power supply dissipating its stored energy and shutting down the supply. This may save the sensitive equipment from damage but turning off the power supply interrupts operations which should be avoided if possible.